no need to lookup window if cursor has not moved (tdf#105575)

use a single-item cache to avoid calling WindowFromPos

Change-Id: I0d42c9572d28363949e38f3e052973727a44fb4a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/120419
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

vcl/win/window/salframe.cxx

@@ -5460,6 +5460,14 @@ void SalTestMouseLeave()
     {
         POINT aPt;
         GetCursorPos( &aPt );
+
+        // a one item cache, because this function is sometimes hot - if the cursor has not moved, then
+        // no need to call WindowFromPoint
+        static POINT cachedPoint;
+        if (cachedPoint.x == aPt.x && cachedPoint.y == aPt.y)
+            return;
+        cachedPoint = aPt;
+
         if ( pSalData->mhWantLeaveMsg != WindowFromPoint( aPt ) )
             SendMessageW( pSalData->mhWantLeaveMsg, SAL_MSG_MOUSELEAVE, 0, MAKELPARAM( aPt.x, aPt.y ) );
     }